The DH bonus? On a somewhat-related note, training to 95 Lockpicking off a GM box and then getting 100 Detect Hidden will not be enough for level 5 chests. This is one of the rare occassions where the game uses your REAL skill instead of shown skill. So if you're got 95 shown lockpicking, 94 real lockpicking, and GM Detect Hidden, you will NOT be able to pick level 5+ chests.
Detect Hidden gives a 5% passive bonus to Lockpicking. So if you have GM Detect Hidden and you pick a lock, you get +5.0 to Lockpicking behind the scenes.
More specifically, DH will give a bonus to lockpicking consisting of (1/20*DH Skill). Meaning that GM DH will give the whole 5 points in lockpicking. This does not affect your shown or real skill, the bonus is applied directly to the skill check when trying to pick a lock.
Was this a ren osi stat or is this server specific becuse I cannot recall ever having that effect way back when